Method of working and governing internal-combustion engines.



T. RIGBY.

METHOD 0? WORKING AND GOVERNING INTERNAL COMBUSTION ENGINES.

APPLICATION FILED OGT.16, 1911.

1,017,592, Patented Feb. 13,1912.

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COLUMBIA PLANOGRAPH CO., WASHINGTON, D c.

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FFICE.

THOMAS RIGBY, OF DUMFRIES, SCOTLAND.

METHOD OF WORKING AND GOVERNING INTERNAL-COMBUSTION ENGINES.

' To all whom it may concern:

Be it known that I, THOMAS RIGBY, a subject of the King of Great Britainand Ireland, and resident of Station Hotel, Dumfries, Scotland, haveinvented certain new and useful Improvements in the Methods of or-kingand Governing of Internal-Oombustion Engines, of which the following isa specification.

This invention relates to improvements in internal combustion enginesand is mainly intended to be used in connection with those enginesworking on the single acting Otto cycle in which an extra charge ofcombustible gas, or air, or a mixture of both is admitted to the workingcylinder in addition to the ordinary working charge drawn in during thesuction stroke.

The type of engine to which the invention is particularly applicable, isthat illustrated in the accompanying drawing and which is known as thevertical tandem type of engine (single acting Otto cycle) in which theupper cylinder is supported by the top of the lower cylinder in such amanner that there is a clearance space between the upper piston at theend of the down stroke and the cover of the lower cylinder, which spacemay be used for compressing and supplying additional gaseous fluid toeither working cylinder by the displacement of the upper piston. Thegaseous fluid is admitted to the clearance space in any suitable manner,but preferably by way of a back pressure valve which closesautomatically at the commence ment of the down stroke of the coupledpistons compressing the gaseous fluid in the clearance space to thenecessary pressure prior to its admission to a working cylinder orreceiver. In 'such an engine the compressed gaseous fluid if delivereddirect is preferably admitted once every revolution to either cylinderalternately and preferably only for the purposes of carrying overload.

Vith such engines as those hereinbefore referred to, there may beexpected to be a little cooling of the additional gaseous fluid (whichis heated by the compression) before it is admitted to the workingcylinder, but this is chiefly owing to radiation losses.

The present invention consists in working internal combustion engines ona new cycle of operations in which additional gaseous fluid is admittedto the working cylinder at or near the end of the suction stroke and iscooled preferably by water prior to its ad- Specification of LettersPatent.

Application filed October 16, 1911.

Serial No. 654,942.

mission to the working cylinder to a temperature below the suctiontemperature usual in engines working on the Otto cycle, for the purposeshereinafter described. The cooling may be effected by bringing the wateror other cooling medium into direct contact with the heated gases or theheated gases into contact with water cooled surfaces, preferably theadditional gaseous fluid being cooled to as near the temperature of theatmosphere or to the temperature of the cooling water as possible priorto its admission to the working cylinder.

According to the invention the cooling required is in practiceconsiderable, and large surfaces are required to eifect it; it isessential that the additional working fluid should be cooled below thetemperature of the ordinary charge and admitted at or near the end ofthe suction stroke, and engines in which but slight cooling of the addedcharge takes place form no part of this invention.

The temperature of the working charge in the cylinder of an ordinaryinternal combustion engine, before compression com- Patented Feb. 13,1912.

mences, has a great influence on the working temperatures, both atcompression and throughout the combustion or power stroke. For instance,in an ordinary Otto cycle engine, the suction temperature at the end ofthe suction stroke is seldom less than eighty degrees Centigrade andoften rises to over one hundred degrees centigrade. If additionalgaseous fluid at atmospheric temperature or thereabout is added to theworking charge the effect of such addition is to reduce the temperatureof the charge before the return of the piston on the compression stroke.For instance, if half the weight of the ordinary working charge is addedin the form of additional gaseous fluid at atmospheric temperature tothe working charge, having at the time a suction temperature of eightydegrees centigrade, the effect will be to raise the pressure in thecylinder to approximately half an atmosphere above that of theatmosphere while the temperature of the mixture will be less than theoriginal eighty degrees centigrade. The direct result of this reductionof tempera ture and increase of pressure before the actual compressionstroke has commenced, is to reduce the maximum temperature of combustionto a much lower temperature, say to the neighborhood of one thousand twohundred to one thousand three hundred degrees centigrade, instead of theusual much higher temperature, without in any way reducing thepercentage of combustible present in the final mixture prior to ignitionand combustion. In consequence the heat losses in the water jacket of aworking cylinder are considerably reduced and a heat gain is effectedwhich is much greater than the heat dissipated by cooling the additionalgaseous fluid before it is admitted to the working cylinder. It isobvious that if additional cooled gaseous fluid be not added to theworking cylinder of an engine of the type indicated the maximumtemperature of combustion will be far higher than the maximumhereinbefore indicated, namely one thousand two hundred to one thousandthree hundred degrees centigrade or thereabout, and as below a certainload it is not economical to introduce the additional cooled gaseousfluid it is therefore preferable that the additional cooled gaseousfluid shall only be admitted to a working cylinder when the load is ator above a predetermined portion of the maximum load,

and the amount of gaseous fluid admitted is governed in accordance withthe load up to the maximum load with maximum delivery of additionalgaseous fluid at maximum load, no additional cooled gaseous fluid beingadmitted when working below the predetermined load.

The governing of the engine is preferably on the throttle system but notnecessarily so, and the predetermined point above referred to is usuallyarranged to be some what below the full load of an ordinary engine(without addition of gaseous fluid) so that the maximum temperature ofcombustion at the predetermined point will not exceed the maximumtemperature of combustion obtained at the maximum load with maximumaddition of cooled gaseous fluid.

)Vhen air only is delivered as the additional charge, it ispreferable'to admit it at or above a predetermined load corresponding tothe maximum temperature desired as hereinbefore described, but at thetime additional air is admitted the proportion of air may beautomatically reduced and the proportion of gas increased in the chargedrawn into the working cylinder during the suction stroke to such anextent that although air under pressure is admitted to the workingcylinder, the final mixture before ignition of the charge is not undulydiluted by excess of air. In all cases where air alone is admitted, theadded air is cooled in the manner above described before its admissionto the working cylinder.

In some cases, the point at which the additional cooled gaseous fluid isadmitted to the working cylinder corresponds to the full load of theengine( without any addition of gaseous fluid), a mixture weak incombustible being drawn into the working cylinder during the ordinarysuction stroke to give a maximum temperature of combustion not higherthan that desired at maximum load with maximum addition of cooledgaseous fluid. In such a case it is preferable that the added cooledgaseous fluid (when a mixture of gas and air) shall be richer in gasthan usual, so that the final mixture at maximum load before ignitionwill be of the full strength required. Any suitable mechanism or valvegear may be used to effect this purpose. When the additional cooledgaseous fluid is gas, the point at which it is admitted preferablycorresponds to the full load of the engine (without addition of gaseousfluid) a weak mixture of gas and air being drawn into the workingcylinder during the ordinary suction stroke of the engine. The ordinarygas supply is preferably in such a case automatically reduced tocorrespond with the addition of cooled gaseous fluid to the workingcharge the mixture being thus altered to the right proportions to insurefull strength of the final mixture at maximum load before ignition andcombustion takes place. hen the additional cooled gaseous fluid is airand a weak mixture is used at full load (without addition ofcooled air)the proportions of gas and air drawn in during the ordinary suctionstroke are automatically altered and the proportions of gas increased toinsure full strength of the final mixture before ignition and combustionat maximum load. Any suitable mechanism or gear may be employed toefiect the above mentioned alterations of the mixture to enable theengine to give maximum power at maximum load if desired in all cases.

In some cases the gaseous fluid in the first place is passed into areceiver or receivers in which it is cooled before it is admitted to aworking cylinder.

The invention may be applied to any Otto type engine in which theadditional gas or air or mixture ofgas and air is obtained by using thedisplacement of the opposite side to the combustion side of a workingpiston to pump the gaseous fluid into a working cylinder or more thanone working cylinder and any modification may be used of the system ofemploying this displacement of the piston or any projection thereof inany desirable manner either passing the cooled gaseous fluid direct tothe working cylinders or by way of a receiver or receivers.

Any of the above mentioned methods of sustaining a miximum load may beemployed in this cycle.

The accompanying drawing is a sectional elevation of a vertical tandemtwo cylinder internal combustion engine, working on the Otto cycle.

In this view, a and b designate the two working cylinders arrangedtandem; c 0 their respective pistons; d the common piston rod upon whichthe two pistons are mounted; p a rod connecting the piston rod 0 to thecrankshaft (not shown) a the compression space formed by closing in theend of the cylinder a; e e the gas or combustible mixture admissionvalves, and f f the exhaust valves of the two working cylinders; g thedelivery valve controlling the pipe 7L leading from the compressionspace a in the working cylinder at to the receiver 2'; 2" an arrangementof cooling tubes placed within the receiver and cooled by water or otherliquid supplied through pipes i and caused to circulate around theoutside of the tubes 2", the heated water passing away through the pipesi j pipes leading from the receiver to the cylinders a b and controlledby extra admission valves is 70 operated by connections 70 from the sideshaft 9, m m the gas and air supply pipes; n the gas, or gas and air,governing valve, and n the connecting rod to the governor forcontrolling the valve and the supply of gas, or gas and air, to thecompression space a of the working cylinder; and Q the side shaft withtwo cams g thereon which operate through connecting rods and links thevalves is and with cams g which operate the exhaust valves Having thusdescribed my invention, what I claim is 1- 1. A method of workinginternal combustion engines in which the main charge is drawn in on thesuction stroke, which consists in admitting to the working cylinder asupplementary charge cooled to a temperature below the temperature ofthe usual charge at or near the end of the suction stroke when the loadof the engine exceeds a predetermined amount.

2. A method of working internal combustion engines, which consists indrawing into the cylinder a charge of gas and air by suction, cooling asupplementary charge to a temperature below the temperature of thefirst-named charge admitting the supple-v mentary charge at or near theend of the suction stroke, compressing the suction charge and thesupplementary charge together, igniting the charge to move the piston onits Working stroke, and permitting the products of combustion to beexpelled on the exhaust stroke.

3. A method of working internal combustion engines, which consists indrawing into the cylinder a charge of gas and air by suction, cooling asupplementary charge to a temperature below the temperature of thefirst-named charge admitting the supplementary charge at or near the endof the suction stroke, compressing the suction charge and thesupplementary charge together, igniting the charge to move the piston onits working stroke, permitting the products of combustion to be expelledon the exhaust stroke, and simultaneously compressing the supplementarycharge for the succeeding explosion.

l. The method of working internal combustion engines which consists indrawing into a cylinder a charge of gas and air by suction,compressing asupplementary charge in the engine, cooling said supplementary chargebelow the temperature of said first named charge, and admitting saidsupplementary charge at or near the end of the suction-stroke.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

THOMAS RIGBY.

Witnesses:

BERTRAM H. MAT'rHEws, H. D. J AMESON.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. G.

